[Tropical] Tropical Weather Discussion

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AXNT20 KNHC 060555
TWDAT

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
105 AM EST THU NOV 06 2008

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL
AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS
OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST
FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED
ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER
OBSERVATIONS...AND RADAR.

BASED ON 0000 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY THROUGH
0515 UTC.

...SPECIAL FEATURE...
THE CENTER OF TROPICAL DEPRESSION SEVENTEEN AT 06/0600 UTC IS
NEAR 14.6N 82.1W OR ABOUT 75 NM EAST-SOUTHEAST OF CABO GRACIAS A
DIOS ON THE NICARAGUA/HONDURAS BORDER. TROPICAL DEPRESSION
SEVENTEEN IS MOVING NORTHWEST AT 4 KT. THE MINIMUM CENTRAL
PRESSURE REPORTED BY THE HURRICANE HUNTER IS 1004 MB. MAXIMUM
SUSTAINED WIND SPEED IS 30 KT WITH GUSTS TO 40 KT. PLEASE SEE
THE LATEST NHC INTERMEDIATE PUBLIC ADVISORY UNDER AWIPS/WMO
HEADERS MIATCPAT2/WTNT32 KNHC AND THE FULL FORECAST/ADVISORY
UNDER AWIPS/WMO HEADERS MIATCMAT2/WTNT22 KNHC FOR MORE DETAILS.
THE DEPRESSION IS EXPECTED TO BECOME A TROPICAL STORM
TODAY...AND ADDITIONAL STRENGTHENING IS FORECAST THROUGH
FRIDAY...WITH A GRADUAL TURN TOWARD THE NORTH FORECAST ON
FRIDAY. THE DEPRESSION IS EXPECTED TO PRODUCE 2 TO 3 INCHES OF
RAIN OVER EASTERN HONDURAS AND NORTHEASTERN NICARAGUA WITH
ISOLATED MAXIMUM TOTALS OF 6 INCHES POSSIBLE. SCATTERED
MODERATE/ISOLATED STRONG CONVECTION IS OVER THE W CARIBBEAN FROM
12N-21N BETWEEN 75W-85W...AFFECTING PORTIONS OF E CUBA...E
HONDURAS...AND NE NICARAGUA.

...THE ITCZ...
ITCZ AXIS IS ANALYZED ALONG 9N13W 7N22W 6N34W 7N44W 6N59W.
SCATTERED MODERATE CONVECTION IS FROM 2N-6N BETWEEN 13W-18W.
ISOLATED MODERATE CONVECTION IS S OF 10N BETWEEN 23W-30W.
SCATTERED MODERATE CONVECTION IS FROM 7N-12N BETWEEN 31W-38W.
THESE AREAS OF CONVECTION ARE BEING ENHANCED BY UPPER LEVEL
DIVERGENCE.

...DISCUSSION...

GULF OF MEXICO...
SOUTHWESTERLY FLOW ALOFT COVERS MUCH OF THE GULF REGION...AS A
DEEP TROUGH OVER THE CENTRAL PLAINS OF THE CONUS ADVANCES
EASTWARD IN THE WAKE OF A DEPARTING UPPER RIDGE. SUBSIDENCE IS
OCCURRING IN ASSOCIATION WITH A SURFACE RIDGE OF HIGH PRESSURE
OVER THE SE CONUS THAT EXTENDS INTO THE GULF. THIS SURFACE RIDGE
IS ANCHORED BY A 1018 MB SURFACE HIGH OVER ALABAMA NEAR 32N87W.
ADDITIONALLY...DEEP LAYER DRY AIR IS PRESENT ACROSS MUCH OF THE
GULF REGION...WHERE STABLE ATMOSPHERIC CONDITIONS PERSIST. THE
COMBINATION OF THE SUBSIDENCE AND DEEP LAYER DRY AIR IS
MAINTAINING GENERALLY FAIR WEATHER CONDITIONS ACROSS THE GULF
REGION.

CARIBBEAN SEA...
TROPICAL DEPRESSION SEVENTEEN IS OVER THE W CARIBBEAN. PLEASE
SEE THE SPECIAL FEATURE SECTION ABOVE FOR MORE INFORMATION ON
THIS SYSTEM. AN UPPER LEVEL HIGH IS OVER THE CENTRAL CARIBBEAN
NEAR 15N73W...WITH THE ANTICYCLONIC FLOW AROUND THE HIGH
COVERING MUCH OF THE CARIBBEAN. TO THE W OF THE HIGH...DEEP LAYER
MOISTURE AND UPPER LEVEL DIVERGENCE ARE PRESENT OVER PORTIONS OF
THE W CARIBBEAN...WHERE TROPICAL DEPRESSION SEVENTEEN IS ALSO
PRESENT. FARTHER TO THE E...DEEP LAYER DRY AIR E OF THE UPPER
HIGH IS RESULTING IN GENERALLY FAIR WEATHER CONDITIONS ACROSS
MUCH OF THE E CARIBBEAN. HOWEVER...ACROSS THE FAR E
CARIBBEAN...UPPER LEVEL DIFFLUENCE AND MOISTURE ARE APPROACHING
FROM THE SW ATLC. THESE FACTORS ARE RESULTING IN SCATTERED
SHOWERS FROM 16N-21N BETWEEN 61W-66W...WHICH ARE AFFECTING THE
LEEWARD ISLANDS.

ATLANTIC OCEAN...
STRONG WEST-SOUTHWESTERLY FLOW ALOFT COVERS THE W ATLC.
ALSO...A COLD FRONT EXTENDS FROM N OF HAITI NEAR 21N72W TO
27N69W TO 32N68W AND EXTENDS N OF THE DISCUSSION AREA. AT THE
SAME TIME...DEEP LAYER MOISTURE FROM THE CARIBBEAN IS
CIRCULATING ANTICYCLONICALLY ACROSS THE SW ATLC AROUND THE UPPER
HIGH IN THE CENTRAL CARIBBEAN NEAR 15N73W. THE COMBINATION OF
LOW LEVEL CONVERGENCE IN THE VICINITY OF THE COLD FRONT AND DEEP
LAYER MOISTURE IS RESULTING IN ISOLATED MODERATE CONVECTION FROM
16N-29N BETWEEN 61W-66W...AFFECTING THE LEEWARD ISLANDS. FARTHER
TO THE E...AN UPPER LEVEL TROUGH IS PRESENT WITH AN AXIS THAT
EXTENDS FROM 8N55W TO 21N49W TO AN UPPER LOW NEAR 32N44W AND
EXTENDS NE OF THE DISCUSSION AREA. THIS UPPER TROUGH IS
ACCOMPANIED BY TWO SURFACE TROUGHS. ONE SURFACE TROUGH EXTENDS
FROM 13N49W TO 18N49W TO 23N46W...WITH SCATTERED MODERATE
CONVECTION FROM 14N-21N BETWEEN 40W-49W. THE SECOND SURFACE
TROUGH EXTENDS FROM 25N45W TO 27N42W TO A 1014 MB SURFACE LOW AT
31N41W. TO THE NE OF THIS SURFACE LOW...A STATIONARY FRONT
EXTENDS FROM 31N41W TO 32N39W TO NE OF THE DISCUSSION
AREA...WITH SCATTERED MODERATE CONVECTION N OF 30N BETWEEN
34W-46W. FARTHER TO THE E...A SURFACE RIDGE EXTENDS FROM A
1028 MB SURFACE HIGH NEAR 36N18W TO 23N28W TO 15N30W...WITH
SUBSIDENCE IN THE VICINITY OF THE SURFACE RIDGE BRINGING FAIR
WEATHER CONDITIONS TO MUCH OF THE E ATLC. OVER THE TROPICAL
ATLC...AN UPPER RIDGE IS PRESENT WITH AN AXIS THAT EXTENDS FROM
15N16W TO 11N24W TO 9N30W...WITH ASSOCIATED UPPER LEVEL
DIVERGENCE ENHANCING THE CONVECTION IN THE VICINITY OF THE ITCZ
AXIS.

$$
COHEN



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